Field
The present disclosure relates generally to optical fibers, and particularly to with low macrobend loss optical fibers.
Technical Background
Glass optical fibers with low attenuation have recently been of significant interest in the telecommunications field. In many optical fibers designed for telecommunications the maximum bend loss at the peak of one of the oscillations can occur in the range of bend diameters of interest, e.g., near the bend diameter prescribed by standards specification, or in the window of bend diameters expected during the deployment. Furthermore, manufacturing process variations that introduce changes in the index profile of the drawn fiber can have a negative impact on the macrobend loss performance. Techniques for improving macrobend properties can play important roles in many types of fibers, including transmission fibers used in long distance applications, multimode fibers used in the emerging area of fiber to the home applications, and dispersion compensation fibers where bending loss has limited many designs from practical use. One technique for minimizing the macrobend loss is by introducing a low refractive index trench (or moat) directly adjacent to and in contact with the fiber core. This can minimize bend loss variability due to shifting bend loss peaks. However, for large effective mode area fibers (fibers with effective areas>100 μm2) this approach is difficult or impractical to apply, because the fiber profile designs that reduce bend loss via the low index trench situated adjacent to the fiber core also usually lead to a longer cutoff wavelength, which often conflicts with the requirements for shorter cabled cutoff wavelength.